One method for preheating glass batch involves feeding cold particulate glass batch raw materials into one end of a rotating heat-transfer drum, and feeding hot media of larger particle size than the batch particles into the other end of the heat transfer drum. The glass batch moves in direct and immediate physical contact with the heated media, with the batch flowing from the cold end to the hot end of the drum and the media flowing from the hot end to the cold end of the drum. The heated particulate batch is removed from the hot end of the drum, and the cooled media is removed from the cold end of the drum. Preferably, the heat transfer media is of a durable material and can be comprised of glass batch agglomerates, glass, ceramic material, steel, stainless steel, aluninum, or gravel. The media can be spherical in shape, and a useable example of such media is spherical ceramic balls. The media can be heated with an external burner or preferably heated by direct contact with exhaust gases from a glass melting furnace.
When the media is heated with furnace exhaust gases, a condensate often collects on the surface of the media. This condensate usually is cleaned off or removed when the media is tumbled with the batch in the rotating drum. Frequently, however, tumbling the media does not remove all the condensate either because the dwell time in the drum is too short or because the coating of condensate is too heavy.